Window shade mechanisms for commercial aircraft cabin windows serve purposes such as darkening the cabin of an aircraft independent of outside light levels and reducing sunlight glare. Applying substantially complete darkening to an aircraft cabin may be desirable for adapting to a destination's time zone, for example, or allowing a movie to be shown from a central screening location without intrusive light.
Glare reduction is often applied by individual passengers by lowering a shade part way, although such solutions may prove unsatisfactory in some cases with existing window shade styles.
A manually operated window shade, the most familiar form of this device, is presently used in many aircraft. While such shades are arguably inexpensive and generally reliable, a window fitted with a manual shade may be difficult to restore if the shade fails, while the shade itself can provide only a limited range of functions—basically, interposing a light-blocking membrane from the top of a window opening as far down as the user chooses.
Air carrier regulations can require shades to be fully open during takeoff and landing. Applying uniform window shade positioning throughout an aircraft generally necessitates cooperation by passengers, while a flight or ground crew member must move from row to row, checking or moving every shade individually, which can be labor-intensive and time consuming.
Typical existing motorized aircraft window shades use fan fold shade media, i.e., media creased into strips and formed into a stack—to extend and withdraw the shade from the viewing area. These designs depend on a combination of durability, self-hinge flexibility, and opacity in the shade media, as well as durability in the remainder of the involved parts, to achieve reliability goals, and have in many cases proven susceptible to wear. In addition, many such designs, constrained by a need to accumulate the fan folded shade media in a generally horizontal stack, are undesirably thick, intruding into the aircraft cabin to a greater extent than is required for other aircraft structural elements, such as fuselage insulation. Such designs additionally can have perimeter light leaks, since the individual panels of the fan folded shade media assume a range of angles, so that a thorough and cost effective light trap along the boundaries of the shade may be extensive in width or infeasible.
Other design approaches can show drawbacks as well. Typical shade designs in which the shade media is gathered on a spool can have limitations comparable to those of fanfold shades. Shade media driven between pinch rollers may rely on roller traction, which is affected by aging, temperature, contamination, and other factors, and can develop misalignment.
Accordingly, it is desirable to provide a method and apparatus that allow the darkening and glare reduction functions of a window shade to be electronically controllable by an individual passenger. It is further desirable that these functions be provided by a shade assembly that has low thickness and weight, that is housed within a self-contained assembly, that exhibits durability and freedom from environmental degradation, and that can be positioned from a remote location.